Field of the Invention:
Embodiments described herein related generally to an apparatus and a method for measuring subcutaneous fat thickness using amplitude mode (A-mode) ultrasound technology.
Description of the Related Art: There are several ways to measure subcutaneous (i.e., under the skin) fat thickness. One method is using a skin fold caliper. By using this method, skin and fat at a measuring spot is pinched and folded. The total thickness is measured using the caliper. The measured thickness depends on how tight the skin and fat layers are pinched. Another problem of using this method is that one can not fold skin and fat layers at certain body locations.
The second method of measuring subcutaneous fat thickness is using ultrasound technology. Studies have been conducted using hospital ultrasound machines to measure skin fat thickness. The fat thickness is obtained by measuring distances on a two-dimensional ultrasound image which is formed using a brightness mode (B-mode) scan. A disadvantage of this method is that the ultrasound machines used in hospitals are expensive.
Another method of measuring subcutaneous fat thickness is using A-Mode ultrasound technology. The basic idea is similar to that of an industrial thickness gauge. The thickness gauge first sends an ultrasound pulse and then receives an echo signal. Based on the known velocity of sound in a measured material and the measured echo time delay (often called “time-of-flight”), the thickness of the measured material can be calculated using a simple formula. However, the human body is more complicated and has multiple layers underneath the skin. The thickness of each layer is not uniform. An industrial thickness gauge that is used for measuring metal thickness can not be used to measure subcutaneous fat thickness of the human body.
An ultrasound device (BodyMetrix™) is available on the market for measuring skin fat thickness. BodyMetrix uses A-mode ultrasound to measure subcutaneous fat thickness. After sending out one ultrasound pulse, the device receives an echo having multiple peaks caused by multiple layers underneath the skin. BodyMetrix assumes that the first strong peak is an echo generated from a fat-muscle boundary. However, the inventor of the current application noticed that this assumption is not always true. Sometimes, BodyMetrix picks an echo peak that is not generated at the fat-muscle boundary. Therefore, the calculated subcutaneous fat thickness is incorrect.